perf stat: Check existence of frontend/backed stalled cycles
Only put the frontend/backend stalled cycles into the default perf stat
events when the CPU actually supports them.
This avoids empty columns with --metric-only on newer Intel CPUs.
Committer note:
Before:
$ perf stat ls
Performance counter stats for 'ls':
1.080893 task-clock (msec) # 0.619 CPUs utilized
0 context-switches # 0.000 K/sec
0 cpu-migrations # 0.000 K/sec
97 page-faults # 0.090 M/sec
3,327,741 cycles # 3.079 GHz
<not supported> stalled-cycles-frontend
<not supported> stalled-cycles-backend
1,609,544 instructions # 0.48 insn per cycle
319,117 branches # 295.235 M/sec
12,246 branch-misses # 3.84% of all branches
0.001746508 seconds time elapsed
$
After:
$ perf stat ls
Performance counter stats for 'ls':
0.693948 task-clock (msec) # 0.662 CPUs utilized
0 context-switches # 0.000 K/sec
0 cpu-migrations # 0.000 K/sec
95 page-faults # 0.137 M/sec
1,792,509 cycles # 2.583 GHz
1,599,047 instructions # 0.89 insn per cycle
316,328 branches # 455.838 M/sec
12,453 branch-misses # 3.94% of all branches
0.001048987 seconds time elapsed
$
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1456532881-26621-2-git-send-email-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
1 file changed